Hybrid torque limiting rotary no-back device

ABSTRACT

A rotary device assembly is provided and includes an input shaft coupled to a torque generating device, an output shaft and a rotary device disposed to transmit first torque from the input shaft to the output shaft and configured with no-back capability to prevent second torque applied to the output shaft from being transmitted to the input shaft in an event the second torque deceeds a torque-limiting threshold and the no-back capability and torsional lock-up capability to prevent an overload of the torque generating device in an event the second torque exceeds the torque-limiting threshold.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 14/486,443 filed on Sep. 15, 2014 which claims thebenefit of priority to U.S. Provisional Application No. 62/026,310,which was filed on Jul. 18, 2014. The entire disclosures of U.S. patentapplication Ser. No. 14/486,443 and U.S. Provisional Application No.62/026,310 are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a rotary device and, moreparticularly, to a rotary device with no-back and torque-limitingcapabilities.

An aircraft utilizes actuation systems for control of aircraft flightsurfaces. Such actuation systems transmit torque to actuators throughtorque transmission devices including torque tubes, gear boxes andbearing supports. If a disconnection failure occurs to a torquetransmission device, a no-back will prevent a loss of position controlfor a given flight surface by grounding the resultant torque generatedby airloads on the flight control surface to a structural ground andthereby lock the surface in a fixed position.

With such flight control actuation systems, it is often necessary tomitigate an overload condition generated by a structural jam. One methodto accomplish overload mitigation is to have a torque limiting devicewithin the actuation system such that the actuator output torque islimited by a mechanism within an actuator by transferring torque tostructural ground if the limit is exceeded.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a rotary device assembly isprovided and includes an input shaft coupled to a torque generatingdevice, an output shaft and a rotary device disposed to transmit firsttorque from the input shaft to the output shaft and configured withno-back capability to prevent second torque applied to the output shaftfrom being transmitted to the input shaft., and the no-back capabilityand torsional lock-up capability to prevent an overload of the torquegenerating device in an event the second torque exceeds thetorque-limiting threshold.

According to another aspect of the invention, a flight control actuationsystem is provided and includes a static surface, a dynamic surface,which is pivotable relative to the static surface and a rotary deviceassembly operably coupled to the static and dynamic surfaces andconfigured to transmit first torque from an input shaft to an outputshaft to control a pivoting of the dynamic surface with independentlypre-loaded no-back capability to prevent second torque applied to theoutput shaft from being transmitted to the input shaft, and the no-backcapability and torsional lock-up capability to prevent an overload of atorque generating device to which the input shaft is coupled in an eventthe second torque exceeds the torque-limiting threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of an aircraft in accordance withembodiments;

FIG. 2 is a view of aerodynamic surfaces of the aircraft of FIG. 1;

FIG. 3 is a perspective view of a rotary device in accordance withembodiments;

FIG. 4 is a side view of a rotary device in accordance with embodiments;

FIG. 5 is a cross-sectional view of the rotary device of FIG. 4 takenalong line A-A;

FIG. 6 is a cross-sectional view of the rotary device of FIG. 4 takenalong line B-B;

FIG. 7 is a cross-sectional view of the rotary device of FIG. 4 takenalong line C-C;

FIG. 8 are side views of operating conditions of a ball ramp mechanismof the rotary device of FIG. 4;

FIG. 9 is a schematic diagram of an operation of the rotary device ofFIG. 4 in accordance with alternative embodiments; and

FIG. 10 is a schematic diagram of an operation of the rotary device ofFIG. 4 in accordance with alternative embodiments.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

A hybrid torque-limiting rotary no-back device with independentpre-loading is provided. The rotary no-back device may be integratedwithin an aircraft flight control actuation system, such as a flapand/or slat high lift system. The no-back capability of the device willprevent an aircraft flight control surface from being displaced from adesired position if a failure occurs to the actuation system's driveline. A torque-limiting capability of the device will prevent overloadof the aircraft structure when the actuation system is loaded beyond thetorque-limiting threshold.

With reference to FIGS. 1 and 2, an aircraft 1 includes a fuselage 2,static aerodynamic surfaces 3 (i.e., wings) extending outwardly from thefuselage 2, dynamic aerodynamic surfaces and engines 5. The engines 5may be attached to the static aerodynamic surfaces 3 or to the fuselage2 and are configured to generate thrust for the aircraft 1. The dynamicaerodynamic surfaces may be provided as flap control surfaces(hereinafter referred to as “flaps”) 40, which are disposed at trailingedges of the static aerodynamic surfaces 3, or slat control surfaces(hereinafter referred to as “slats”) 41, which are disposed at leadingedges of the static dynamic surfaces 3. The flaps 40 are configured tobe pivoted relative to the static aerodynamic surfaces 3 by flapactuators 42, which are controlled and driven by a flap power drive unit43. Similarly, the slats 41 are configured to be pivoted relative to thestatic aerodynamic surfaces 3 by slat actuators 44, which are controlledand driven by a slat power drive unit 45. As shown in FIGS. 2 and 3, theflap actuators 42/slat actuators 44 of the aircraft 1 may each include arotary device assembly 6 operably coupled to at least one of the staticaerodynamic surfaces 3 and to an associated one or more of the flaps 40and the slats 41 to execute the pivoting actions thereof.

The rotary device assembly 6 is configured to transmit a first torquefrom an input shaft 7, which is rotatable relative to the staticaerodynamic surface 3, to an output shaft 8, which is non-rotatablerelative to the dynamic aerodynamic surface 4. By way of such torquetransmission, the rotary device assembly 6 is able to control a pivotingof the dynamic aerodynamic surface 4 with independently pre-loadedno-back capability and, in some cases, with no-back capability andtorsional lock-up capability.

As will be described below, the no-back capability of the rotary deviceassembly serves to prevent second torque, which may be applied to theoutput shaft 8 by external forces acting on the flap 40/slat 41 frombeing transmitted to the input shaft 7 in an event the second torquedeceeds (i.e., is less than) a torque-limiting threshold. The torsionallock-up capability serves to prevent an overload of a torque generatingdevice, such as the flap power drive unit 43 and the slat power driveunit 45, to which the input shaft 7 is coupled in an event the secondtorque exceeds the torque-limiting threshold.

With reference to FIG. 4, the rotary device assembly 6 includes theinput shaft 7, which is coupled to the flap power drive unit 43 or theslat power drive unit 45 and which is rotatable relative to the staticaerodynamic surface 3 (see FIGS. 2 and 3) in accordance with torquebeing generated by the flap power drive unit 43 and the slat power driveunit 45, the output shaft 8, which is non-rotatable relative to the flap40/slat 41, and a rotary device 10. The rotary device 10 is operablydisposed to transmit first torque from the input shaft 7 to the outputshaft 8 along an input toque pathway 11 and is configured with theindependently pre-loaded no-back capability to prevent the second torquefrom being transmitted to the input shaft 7 in the event the secondtorque deceeds a torque-limiting threshold and with both the no-backcapability and torsional lock-up capability to prevent an overload ofthe flap power drive unit 43 and the slat power drive unit 45 in anevent the second torque exceeds the torque-limiting threshold.

The rotary device assembly 6 further includes an actuator or firstsupport housing 12, bearing elements 13 and a second support housing 14.The first support housing 12 may be supportively disposed within thestatic aerodynamic surface 3 and the bearing elements 13 are disposedbetween the first support housing 12 and the input shaft 7 to therebyrotatably support the input shaft 7 in the support housing 12. Thesecond support housing 14 may be static relative to the staticaerodynamic surface 3 and may be configured as an anchor to which therotary device 6 may be anchored.

The rotary device 6 also includes an input portion and an outputportion, both of which will now be described with continued reference toFIG. 4 and with additional reference to FIGS. 5-8. The input portionincludes a ball ramp thrust plate 15, an output cone shaft 16 and (e.g.,three) spherical balls 17. The ball ramp thrust plate 15 extendsoutwardly from the input shaft 7 and is torsionally coupled to the inputshaft 7 via a roller 70, a spline or another suitable device. The outputshaft 8 is torsio.

Finally coupled to the output cone shaft 16 by a spline or othersuitable means and is pre-loaded by a spring (hereinafter referred to asa “first elastic element”) 18 and is rotatable with the output shaft 8.The thrust plate 15 has a first axial surface 150, which is formed todefine dimples 151, and the output cone shaft 16 has a second axialsurface 160, which is formed to define three ramps 161. The first andsecond axial surfaces 150 and 160 are complementary and face toward oneanother in opposite axial directions.

The spherical balls 17 may each be disposed to partially sit within thedimples 151 on one side thereof and within the ramps 161 on the otherside thereof. In this condition, first torque generated by the flappower drive unit 43 or the slat power drive unit 45 is provided to theinput shaft 7 and the thrust plate 15, and from the thrust plate 15 tothe spherical balls 17 and from the spherical balls 17 to the outputcone shaft 16 and the output shaft 8. However, while the spherical balls17 cannot be forced laterally out of the dimples 151, the sphericalballs 17 can be forced or driven laterally out of the ramps 161 alongramped portions 162, which are each shallower compared to the rest ofthe rims of the ramps 161 and the rims of the dimples 151 as will bedescribed below.

The first elastic element 18 is pre-loaded to effectively sandwich thespherical balls 17 between the first and second axial surfaces 150 and160 with a force that maintains respective positions of the sphericalballs within the dimples 151 and the ramps 161 to thereby define atorque-limiting threshold. That is, as long as the second torque deceedsthe torque-limiting threshold, the spherical balls 17 will remaindisposed in the dimples 151 and the ramps 161. However, once the secondtorque exceeds the torque-limiting threshold, the spherical balls 17will be driven along the ramped portions 162 and thus removed from atleast the ramps 161. The combination of the output cone shaft 16, thespherical balls 17, the first elastic element 18, the dimples 151 andthe ramps 161 may be collectively referred to as a ball ramp assembly.

As shown in FIG. 4, the output cone shaft 16 has an exterior surfacethat has an elongate portion and a distal end that is formed to define adynamic cone portion 19. The dynamic cone portion 19 includes a conicalsurface 190 having radial and axial facing components. With the dynamiccone portion 19 formed as such, the output portion of the rotary device6 includes a first torque pathway 20 and a second torque pathway 21.

The first torque pathway 20 is activated in the event the second torquedeceeds the torque-limiting threshold. In such cases, the pre-load ofthe first elastic element 18 causes the second torque to be transmittedfrom the output cone shaft 16 to a skewed bearing set (hereinafterreferred to as a “first skewed roller assembly”) 201 via the thrustplate 15 with the first skewed roller assembly 201 being operablycoupled to the first support housing 12. Thus, the first torque pathway20 directs the second torque away from the input shaft 7.

The second torque pathway 21 also directs the second torque away fromthe input shaft 7 and, in addition, adds the second torque to a torquegain generated by a cone portion engagement to be described below. Thesecond torque pathway 21 includes a static cone portion 211, whichincludes a conical surface 212 having radial and axial facing componentscomplementing those of the conical surface 190 of the dynamic coneportion 19 and is coupled to the second support housing 14.

The second torque pathway 21 is activated in the event the second torqueexceeds the torque-limiting threshold, in which case the spherical balls17 will be driven along the ramped portions 162 and thus removed from atleast the ramps 161 such that the output cone shaft 16 is forcedradially outwardly. With the output cone shaft 16 being forced radiallyoutwardly, the dynamic cone portion 19 engages with the static coneportion 211 and resulting gain from the engagement provides for atorsional lock-up of the input portion of the rotary device 6 due toaxial loading proportional to the second torque being reacted to bysecond skewed roller assembly 212. This results in a lock-up of thesecond skewed roller assembly 212, which creates a torsional ground forthe engaged dynamic and static cone portions 19 and 211. The dynamiccone portion 19, the static cone portion 211, the first skewed rollerassembly 201 and the second skewed roller assembly 212 may becollectively referred to as a high gain cone brake assembly.

In accordance with embodiments, the second skewed roller assembly 212may be provided as a pre-loaded skewed roller assembly operably disposedbetween the static cone portion 211 and the thrust plate 15. Thispre-loaded skewed roller assembly includes a spring set (hereinafterreferred to as a “second elastic element”) 22, which is anchored on thesecond support housing 14, and a thrust bearing assembly (hereinafterreferred to as a “skewed roller bearing”) 23, which is coupled to adistal end of the second elastic element 22. The second elastic element22 may be provided as a wave spring that acts as an independentpre-loading spring that in turn allows for pre-loading of the secondskewed roller assembly 212 without negatively impacting activation loadrequirements of cone brake ball ramp assembly and provides for no-backdrag torque to mitigate unintended rotation/creep over all loadconditions and vibration environments.

In an operation of the rotary device 10, the input shaft 7 istorsionally coupled to the ball ramp thrust plate 15 via roller 70 asnoted above. The ball ramp thrust plate 15 is also axially pre-loaded bythe second elastic element 22. The skewed roller bearing 23 provideslimited torsional friction between the ball ramp thrust plate 15 and thesecond elastic element 22 with the second elastic element 22 providingan axial load to the first skewed roller assembly 201. The first skewedroller assembly 201 may be provided with an anti-rotation feature 2010and a number of needle rollers 2011 skewed at about a 45° angle, forexample. The skewed angle of the needle rollers 2011 and the loadproduced by the second elastic element 22 produces torsional drag on theball ramp thrust plate 15 that is proportional to the applied axialload. The load value of the second elastic element 22 and the skew angleof the needle rollers 2011 of the first skewed roller assembly 201 canbe varied to any combination to provide an appropriate torsional drag onthe ball ramp thrust plate 15. In addition, the first skewed rollerassembly 201 may be provided as a single feature or as multiple stackedfeatures.

The torsional drag created by the second elastic element 22 may be sizedto react to back drive loads applied to the output shaft 8 and which areconsidered within the normal operating threshold (i.e., the back driveloads are less than the torque-limiting threshold). As such, thisconstant drag will eliminate chatter that some other no-back designs canproduce by an engaging and disengaging design approach.

With reference to FIGS. 8 and 9, under a normal and intact operatingcondition where input torque opposes loadings below the torque-limitingthreshold, the input torque applied to the input shaft 7 and into ballramp thrust plate 15 via roller 70 is transmitted to the ball rampassembly (see also input torque pathway 11 of FIG. 4). The ball rampassembly then transmits a torsional load to the dynamic cone assembly 19and the output shaft 8 through the drag torque generated by way of biascreated by the first elastic element 18, which loads the ball rampassembly to force the spherical balls 17 to the bottom of the ramps 161as shown in the left-side image of FIG. 8. The ramped portions 162 ofthe ramps 161 will have an appropriate angle in combination with thebias applied by the first elastic element 18 to allow for the torsionaltransmission without causing the spherical balls 17 to be driven up theramped portions 162. Torque transmitted to the dynamic cone portion 19is then reacted through the interface between the dynamic cone portion19 and the output shaft 8 (this interface may include a spline or othersuitable torque transmitting device). The dynamic cone portion 19 andthe static cone portion 211 have a clearance maintained by the forcecreated by the first elastic element 18 such that the cones remaindisengaged.

With reference to FIGS. 8 and 10, under a torque limiting event or aback driving event, with torsional loads above a normal operating loadthreshold, the spherical balls 17 will be forced up the ramped portions162 of the ramps 161 as shown in the right-side image of FIG. 8 tothereby generate an axial force that is proportional to torque appliedto the ball ramp assembly. The axial force is reacted by the now-engagedcones and the first skewed roller assembly 201. The axial force reactedthrough the ball ramp thrust plate 15 to the first skewed rollerassembly 201 creates a drag torque that is proportional to the axialforce applied to the first skewed roller assembly 201, which has ahigher magnitude than the drag torque created by the first elasticelement 22, while the cone engagement creates a high gain brakingcondition.

The high gain braking condition may be characterized as a wedging actionbetween the engaged dynamic cone portion 19 and the static cone portion211, which is torsionally grounded to the second support housing 14. Thehigh gain (>1) of the cone engagement creates an internal torqueresistance that is greater than the torque applied to the output shaft 8based on the wedging action of the cones generated by the axial force ofthe ball ramp assembly. To disengage the cones, a torque must be appliedto the input shaft 7 in an opposite direction of rotation from thenormal direction of rotation such that the ball ramp thrust plate 15 isrotated to thereby allow the spherical balls 17 to move back down theramped portions 162 of the ramps 161.

In accordance with embodiments, materials for the various componentsdiscussed above may include at least one or more of steels, aluminum andbronze with the various components further having a Teflon™, Kevlar™,Carbon or Ceramic coating.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A rotary device, comprising: a thrust plate rotatable with an inputshaft and having dimples defining first surfaces; an output cone shaftrotatable with an output shaft and having ramps defining second surfacescomplementing the first surfaces; and spherical balls disposable forinput-output shaft torque transmission in the dimples and the ramps anddrivable out of the ramps if a second torque applied to the output shaftexceeds a threshold, the second torque being prevented from transmissionto the input shaft if the second torque deceeds the threshold, anoverload of a torque generating device to which the input shaft iscoupled being prevented if the second torque exceeds the threshold, andthe rotary device further comprising an elastic element by which theoutput cone shaft is coupled to the output shaft and which is pre-loadedto prevent engagement of overload prevention if the second torquedeceeds the threshold.
 2. The rotary device according to claim 1,wherein the torque generating device comprises a flight controlactuation system.
 3. The rotary device according to claim 1, furthercomprising: a first support housing; bearing elements by which the inputshaft is rotatably disposed in the support housing; and a second supporthousing to which the rotary device is anchored.
 4. The rotary deviceaccording to claim 1, wherein the output cone shaft comprises a dynamiccone portion and the rotary device further comprises: a first torquepathway, which is activated if the second torque deceeds the thresholdand which is directed away from the input shaft; and a second torquepathway including a static cone portion, which is activated if thesecond torque exceeds the threshold and by which the second torque isdirected away from the input shaft and added to a torque gain generatedby engagement between the dynamic cone portion and the static coneportion.
 5. The rotary device according to claim 4, further comprising:a roller assembly operably disposed between the thrust plate and asupport housing; and a pre-loaded roller assembly operably disposedbetween the static cone portion and the thrust plate, wherein the rollerassembly is loaded for providing variable drag torques.
 6. A flightcontrol actuation system, comprising: a dynamic surface pivotablerelative to a static surface; and a rotary device assembly comprising:an output portion with a skewed roller assembly loaded by pre-loadsprings and a ball ramp assembly such that the skewed roller assemblyprovides variable drag torques which are variable based on the loads ofthe pre-load springs and the ball ramp assembly; a ball-ramp assembly;and a high gain cone brake assembly, the rotary device assembly beingconfigured for input-output shaft torque transmission to control apivoting of the dynamic surface while preventing output-input shafttorque transmission if torque applied to an output shaft deceeds athreshold and while preventing an overload of a torque generating deviceto which an input shaft is coupled if the torque applied to the outputshaft exceeds the threshold.
 7. The flight control actuation systemaccording to claim 6, wherein the static surface comprises a wing andthe dynamic surface comprises a flap or a slat.
 8. The flight controlactuation system according to claim 6, wherein the torque applied to theoutput shaft is applied via the dynamic surface.
 9. The flight controlactuation system according to claim 6, wherein the torque generatingdevice comprises a motor.
 10. The flight control actuation systemaccording to claim 6, wherein the rotary device assembly furthercomprises an input torque pathway and first and second torque pathwaysdisposed in a reverse orientation relative to the input torque pathway.